arch/x86/Kconfig: Add deprecation warnings for LATE_CBMEM_INIT

The deprecation of late (post-romstage) CBMEM initialization was
announced in this blog post:
https://blogs.coreboot.org/blog/2017/05/08/announcing-coreboot-4-6/

There are two warnings:
* In LATE_CBMEM_INIT's help text, I've added a multi-line warning, that
  aims to explain the problem.
* In src/mainboard/Kconfig (just below the mainboard selection), there's
  a warning which points the user at LATE_CBMEM_INIT, if such a board is
  selected.

Also update the function that needs to be implemented, as pointed out by
Keith Hui and Kyösti Mälkki.

Change-Id: I2d21a6ab2fc2811d44fc4febb05841bb2f8d1857
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/21112
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

0 files changed, 0 insertions, 0 deletions